Anti-Histamines Flashcards
How many Histamine Receptors do we have
4
We have specific drugs for which>
H1 and H2
H1 antagonists prevent what>
Watery eyes, redness, erythema, etc….
Which class of H1 inhibitors has the longer duration?
1st generation
Which can cross the blood brain barrier?
1st generation, These drugs can cross the blood brain barrier due to their lipophilic nature. They bind H1 in the brain
What does the H1 binding site in the brain usually control
Wakefullness and alertness, It is located in the hypothalamus.
What happens when you block this H1 binding site in the brain?
You get the opposite of wakefulness—-> sedation
ANTI-Cholinergic
What are the four 1st generation drugs we need to know
Diphenhydramine, Dimenhydrinate, chlorampheniramine, Hydroxyzine
What are the 2nd generation drugs we need to know
Fexifenadrine and cetrizine
WHich of the first genereation drugs is no where near as sedating as the other two?
Chlorpheniramine
Why can’t first generations be used in asthmatics?
Because they decrease cilliary beating
Why wouldnt you want to give a first generation antihistamine to a pt with BPH
Because it causes further urinary retention
What are the other side effects of 1st gen drugs
hypotension and reflex tachy, increased appetite, QT prolongation
